Field of the Invention
The present invention relates to a printing apparatus for performing a printing for a printing medium with the use of an ink head for ejecting ink and a treatment liquid head for ejecting treatment liquid to control printing properties of the ink, a printing head unit usable for the printing apparatus, a liquid tank unit adapted to be mounted on the printing head unit, and a printing method.
In recent years, with respect to an ink jet printing apparatus for forming an image by ejecting ink from a printing head to a printing medium such as a paper, a film, a cloth or the like (hereinafter referred to as a printing sheet), a technology having treatment liquid additionally used for improving water resistance of the ink and controlling properties of the ink so as to print an image with high quality. The treatment liquid has a function for suppressing the blur of the ink by suppressing the penetration of the ink to the printing sheet or promoting the drying of the ink. The treatment liquid is ejected to the printing sheet before the ink is ejected or the treatment liquid is ejected to the printing sheet directly after the ink is ejected. An ink jet printing apparatus of the foregoing type is known as disclosed in Japanese Patent Application Laying-open No. 15-128862.
A conventional ink jet printing apparatus is basically designed so as not to allow the ink to leak from an ink supplying tank. However, there is a fear that ink leaks from a connecting portion between a printing head and an ink supplying tank for some reason, e.g., radical variation of the atmosphere pressure exerted on the ink supplying tank. For this reason, there arises a necessity that printing operation is not incorrectly performed even though the ink leaks in the aforementioned manner. For example, Japanese Patent Application Laying-open No. 60-85964 discloses a dish-like member for receiving the leaked ink from the ink supplying system, the whole ink supplying system arranged on the dish-like member. In addition, there is known the printing apparatus that while the bottom of a housing have not any opening portion so as not to leak the ink. In addition, Japanese Patent Application Laying-open No. 09-024618 discloses that the ink leaked from an ink supplying system is conducted to a specific discharging passage arranged in the printing apparatus, and moreover, the ink is additionally conducted to an ink drain tank from the discharging passage.
With respect to an ink jet printing apparatus adapted to perform a printing by ejecting to a printing sheet the treatment liquid to control printing properties of ink before the ink is ejected or after it is ejected, in the case that a conventional measure is employed to the printing apparatus for ink leakage, there appear problems as noted below when leakage of both of the ink and the treatment liquid occurs.
(1) In the case that a technology for completely covering the bottom of the printing apparatus is employed, there is a fear that the ink and the treatment liquid react with each other and they are solidified, causing the vicinity of a supplying port for supplying ink from an ink supplying portion to a printing head to be closed due to the solidification of the ink and the treatment liquid, and moreover, sealing properties of a printing head relative to the surface of a plurality of ejecting ports are degraded due to adhesion of the solidified ink to a cap head disposed for the printing head. PA1 (2) In the case that the technology for conducting leaked ink to an ink drain tank via a specific discharging passage is employed, there is a fear that the discharging passage is closed due to the reaction of the leaked ink with the leaked treatment liquid in the discharging passage. Thus, there is a fear that the ink or the treatment liquid which leaks later flows out from the discharging passage into the interior of the printing apparatus or flows out from the printing apparatus and it is then solidified with the result that the printing apparatus and associated components are seriously damaged. PA1 ink head restoring means for performing restoring for the ink head by sucking ink from the ink ejecting ports, PA1 an ink drain tank for receiving the ink sucked by the sucking operation of the ink head restoring means, PA1 leaked ink conducting means for conducting the ink leaked from the first ink supplying tank to the ink drain tank, PA1 treatment liquid restoring means for performing restoring for the treatment liquid head by sucking treatment liquid from the treatment liquid ejecting ports, PA1 a treatment liquid drain tank for receiving the treatment liquid sucked by the sucking operation of the treatment liquid head restoring means, and PA1 leaked treatment liquid conducting means for conducting the treatment liquid leaked from the first treatment liquid supplying tank to the treatment liquid drain tank. PA1 an ink supplementing port connected to an ink supplying port of the ink supplying tank, PA1 a treatment liquid supplementing port connected to a treatment liquid supplying port of the treatment liquid supplying tank, PA1 a rib for surrounding the periphery of the ink supplementing port and defining a enclosed space for conducting the ink leaked from wall surface of the ink supplying tank, and for surrounding the periphery of the treatment liquid supplementing port and defining a enclosed space for conducting the treatment liquid leaked from wall surface of the treatment liquid supplying tank, PA1 an ink discharging opening portion defined on the rib for discharging the ink in the enclosed space to which the ink supplementing port is exposed, and PA1 a treatment liquid discharging opening portion defined on the rib for discharging the treatment liquid in the enclosed space to which the treatment liquid supplementing port is exposed. PA1 a leaked ink discharging passage for conducting the ink leaked from the ink supplementing tank to a enclosed space defined between the printing head unit and the liquid tank unit, and PA1 a leaked treatment liquid discharging passage for conducting the treatment liquid leaked from the treatment liquid supplementing tank to the enclosed space separately from the ink. PA1 a step for detecting the presence or absence of ink leakage between the ink supplying tank and the ink head, PA1 a step for detecting the presence or absence of treatment liquid leakage between the treatment supplying tank and the treatment liquid head, and PA1 a step for informing an occurrence of leakage of ink or treatment liquid in the case that ink leakage or treatment liquid leakage occurs, and then for stopping the printing operation.